Traditionally, guitars have a headstock opposite a tail. The head includes a headpiece having tuning pegs to which the first ends of the guitar strings attach. The strings extend along a fretboard to the body of the guitar where, at their second ends, they mount to a bridge which, typically, extends generally perpendicular to the length of the strings. In such a configuration, the bridge has a front side which is nearer to the head of the guitar, and a rear side which is nearer to the tail of the guitar. In such a guitar, the bridge is rigidly mounted to the body of the guitar.
In roughly 1954, Fender Guitar Corp. patented a new design for a guitar bridge used with an electric guitar, a design commonly referred to as a “fulcrum-style tremolo bridge.” A fulcrum-style tremolo bridge allows a guitar player to raise and lower the pitch of the strings by pulling up on, or pushing down on, a tremolo arm that is attached to the bridge. In a fulcrum-style tremolo bridge, a first side of the bridge is held in tension against the body of the guitar, wherein the bridge can pivot at its contact point with the body. In one such type fulcrum-style tremolo bridge, referred to as a Wilkenson bridge, the front side of the bridge has a blade edge which is held in tension against a pair of posts mounted to the body of the guitar, and the bridge is able to pivot at the connection between the blade edge and the posts (described infra). In another fulcrum-style tremolo bridge, the tremolo bridge pivots based on a number of fasteners (e.g., screws) which extend through the front portion of the tremolo bridge and into the body.
The embodiments discussed herein are discussed relative to such a Wilkenson bridge. For instance, using language like “at least one post extending from said body, each of said at least one post further comprising a V-shaped notch.” However, such language is intended to include other such floating bridges, including the original fender “six hole” fulcrum bridge wherein the bridge attaches loosely to the body of the guitar using screws, and it is the contact with the screws that serves as the pivotal connection that is the equivalent to the edge pivoting in the V-shaped notch of a post described herein.
In a fulcrum-style tremolo bridge, in general, the rear side of the bridge “floats” and is not mounted to the body of the guitar. The bridge further includes a block attached to the bottom of the bridge which passes through the guitar. Attached to this block are springs that run forward from the block toward the neck of the guitar. The springs counter-balance the tension of the strings of the guitar, holding the strings of the guitar in tune in a default position where the strings' tension is generally equal to springs' tension. In such a configuration, the bridge can pivot upwards and downwards generally around an axis that is defined by the point where the blade edge of the bridge contacts the posts of the body.
When the guitar is in tune, the bridge lies somewhere between the limits of the distance that it can pivot. When the rear side of the bridge pivots upwards (away from the body of the guitar), the pitch of the strings is lowered; whereas when the rear side of the bridge pivots downwards (towards the body of the guitar), the pitch of the strings is raised.
A traditional fulcrum-style tremolo bridge has a commonly known limitation that occurs when the guitar player bends a string to raise its pitch. When one string is bent, the tension generated by bending the string overcomes the opposing tension from the springs, and the rear side of the bridge will pivot upwards (away from the body of the guitar). This pivoting motion may result in the pitch of all of the strings changing (not just the string bent). Further, this pivoting motion may result in the pitch of the strings changing unequally. For instance, when the bridge is pivoted all of the guitar's strings change equally in length but change unequally in pitch. This occurs due to the difference in each string's diameter. Thus, even a relatively small pivoting motion results in a pitch change across multiple strings. Because of this, a problem exists for a guitarist who may want to play other notes or chords on the other strings while the bent string is bent.